Pumps of this type are well known and comprise essentially a main hollow body of circular cross-section composed of coaxial portions of different diameter and housing all the pump operating members, including a coaxial stem projecting from one of the open ends of the main body. The stem is operated to deliver the substance contained in the bottle.
Specifically, delivery is obtained by pressing axially with the hand, in the direction of the main body, on a suitable knob fixed to the end of the stem projecting from the main body. The stem is returned to its rest or non-delivery position by the action of a return spring when the axial pressing action ceases.
The individual operating members of the pump are currently supplied to the user separate from each other and from the main pump body. The user must therefore manually assemble the various component pieces of the pump and finally close the aperture in the main body from which the stem extends by means of a cap having a coaxial hole through which the stem projects. The cap is not fixed to the main body and can only rest on one end of it. At an intermediate point on the stem there is provided a projecting collar which rests against the inner face of the cap to form a travel stop for the stem and thus define the rest position. A suitable gasket can be interposed between the collar and the cap. The return spring keeps the stem in its rest position.
The pump is fixed either directly to the bottle mouth or to a suitable ring nut which is then fixed to the bottle mouth. The ring nut can also be integral with the main body.
The bottle mouth, or the associated ring nut if not integral with the main body, are shaped to retain the cap in position together with the main pump body and the operating members contained in it. As stated, this cap only rests on the main body. Consequently, the various operating members which make up the pump can be maintained in position only when the pump has been fitted to the bottle or to the associated ring nut.
For further details of known pumps, reference should be made to utility model application No. 19981 A/87 and to USA Pat. No. 4,607,765.
As is apparent, manual assembly of the various component pieces of the pump is rather long and delicate because of the small size of some of these components and the fact that some pieces remain in position only after the cap has been added and the pump fitted to the bottle or ring nut. All this substantially influences bottling costs.